For that matter it isn't clear why he was glorified. To Moscow he was a "passion bearer" and to the ROCOR a "martyr." For what cause he was actually a matyr... who knows. Only time will tell if his cult is a real thing or if it merely fades away in coming generations.
In most of the hagiography the reason both ROCOR and Moscow accept he and his family as saints has to do with their personal belief and devotion as a family to the Church and to the Saints. They cite numerous practices of piety and charity of both the Tsar and Tsarina. The hagiography notes that the Royal Family continued to try to influence the decadent Imperial court to do individual acts of charity,nursing of the sick and wounded, sewing, and support of the widowed and the orphan. (Did you know that at the time of the Revolution, 80% of the income of the Royal Family was being used to support widows, orphans, the private schooling of orphans, scholarships to the seminaries for promising students, monasteries, and convents, shelters for women, industrial education centers and housing programs, cultural schools like the Bolshoi and other arts schools?)
The Tsar's abdication was to prevent additional bloodshed and is noted in the letters of the government and those who witnessed it. Under House arrest first by the Provisional government and the Bolsheviks, the Royal family remembered that they were truely God annointed rulers and accepted abuse and ridicule as a cross they must bear in Christ's love (read the journals of the family and you will see this vividly in their most personal entries.) Tsar and Tsarina refused to participate in white Russian plots and plans for their rescue for fear of those who would be injured by such action.
To the Moscow Patriarchate, this qualified them for Passionbearers just as Boris and Gleb qualified for passionbearers for the same reason.
To the ROCOR Synod, the facts behind the decision of Lenin to assure that the royal, annointed bloodline of the Romanovs was fully eliminated as Christian rulers coincided withthe planned distruction of the Russian Orthodox Church which included not only the Royal family but the other New Martyrs of the Bolshevik Yoke that includes Rishops, Monks, Nuns, Priests, Nobleman, and peasant. Lenin's writings descibe the need to eliminate the Tsar as the focal point of Holy Russia and the Orthodox Church.
Tsar Nicholas II was not glorified for his actions as a ruler, but for personal piety, and passionbearing in the presence of actions that many of us might run from. His diary , written in English by the way, presents the trumoil that he often felt as an autocratic ruler and the fact that he felt wholly unprepraed for this role. His retreat into his family and their spiritual practices show the true life of The Holy Passionbearer Tsar Nicholas II, His Tsarina, and his children. The effect of a Orthodox Christian rearing of children in a home filled with Christian Love led them to become passionbearers and exemplify Christian behavior to those who sought to destroy them physically and spiritually. They were destroyed in the flesh but they retained their spiritual witness. This is the value of the Romanov Passionbearer's witness to me.
For this reason members of my family(1 daughter and three grandchildren)bear as their patronal saints, the names of the Romanov family .